1. Field of the Invention
The present invention relates to a surveillance television camera having a dome cover, and more particularly to such a surveillance camera in which a dome cover is detachably attachable to a base of the camera.
2. Description of the Related Art
Surveillance television cameras are conventionally provided with a transparent or translucent dome cover which covers a television camera body for the purposes of waterproof and dustproof or in order that the directionality of a camera lens may be hidden. JP-A-2006-074657 discloses a surveillance television camera to which a bayonet dome cover is detachably attachable. In the disclosed camera, a locking recess is formed in an engagement piece provided on a joint surface of the dome cover to the camera base. The camera base has a joint surface to the dome cover. The joint surface of the camera base is provided with an engagement groove which has an inner end formed with an engagement protrusion. The engagement recess and protrusion are engaged with each other in a bayonet manner so that the dome cover is detachably attached to the camera base.
However, when the dome cover is attached to the camera base in the bayonet manner, it is difficult to understand whether the engagement recess and protrusion are reliably engaged with each other. Furthermore, when the engagement is insufficient, the dome cover is caused to turn in a direction opposite to an attaching direction, whereupon the dome cover may fall off.